/Engine/Source/Runtime/UMG/Public/Blueprint/UserWidget.h
The system will use this event to notify a widget that the cursor has entered it. This event is NOT bubbled.
void OnMouseEnter ( [FGeometry](API\Runtime\SlateCore\Layout\FGeometry) MyGeometry, const [FPointerEvent](API\Runtime\SlateCore\Input\FPointerEvent) & MouseEvent )